Facebook came under fire after the revelation that the social media giant
manipulated users' News Feeds for an emotion study.

The
newsfeed manipualtion was used to to see if it made users feel blue. This
activity now has some users seeing red.

Facebook received backlash after participating in a study that saw the
company clandestinely tweaking content seen by more than 700,000 users for a
psychology experiment.

The research was an experiment as part of product testing, Sandberg told a
women's business seminar in New Delhi when asked whether the study was
ethical.

"This was communicated terribly and for that communication we have
apologised," she said.

"We communicated really badly on this subject," she said, before adding: "We
take privacy at Facebook really seriously."

Researchers did not
tell users the News Feed manipulation would be taking place, however, the
actions by Facebook is legal due to terms laid out in the user agreement when an
individual signs up for the site.